1. Field of the Disclosure
This disclosure generally relates to exploration and production of hydrocarbons involving investigations of regions of an earth formation penetrated by a borehole. More specifically, the disclosure relates to the characterizing the earth formation using a logging tool in the borehole.
2. Description of the Related Art
The exploration for and production of hydrocarbons may involve a variety of techniques for characterizing earth formations. Drilling boreholes in earth formations may lead to the build-up on impermeable substances, such as mudcake, on borehole walls. The impermeable medium may separate the borehole fluid from the porous earth formation that may be of interest. The impermeable medium may also reduce accuracy of permeability measurements of the earth formation using techniques commonly used in the field of hydrocarbon exploration and production.
Acoustic borehole logging instruments are used to measure velocities of earth formations in one or more modes of acoustic energy propagation. Acoustic borehole logging instruments are typically used in liquid-filled boreholes drilled through the earth formations. Velocity may be generally determined using these instruments by measuring the time taken by an acoustic energy pulse to traverse a particular distance along the wall of the wellbore. The wall forms the interface between the liquid in the wellbore and the earth formations.